A stringline is often employed in the prior art as a guide for an automatic machine control used in construction work. The stringline must be properly disposed both horizontally and vertically so that the machine under control will be accurately guided along a required path.
In general, a stringline is supported on a stringline rod, which is usually horizontally disposed and formed with a stringline engaging groove. The stringline rod is clamped to a vertically disposed ground stake by an adjustable clamp.
A plurality of spaced stringline rods with their grooves aligned on the guide locus hold the stringline on the proper guide path. This prior art arrangement is satisfactory for straight-line guides, or large-radius curves; but for guide curves having a relatively small radius, such as a small circle, the guide path is defined in a series of straight-line-segments. These straight-line segments cause the guided machine to similarly operate in corresponding straight-line segments. The resulting construction is unsatisfactory for high quality specifications.
In certain construction situations, the supervising foreman will attempt to minimize the effect of the straight-line segments by very closely spacing the ground stakes and their supported stringline rods. This alternative is time consuming and therefore costly.